Applications of Ion-Implanted Covalent Polymers
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APPLICATIONS OF ION-IMPLANTED COVALENT POLYMERS
DAVID C. WEBER, MARIANNE K. BERNETr, AND HAROLD RAVNER Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375
ABSTRACT Materials presently used for packaging precision instrument bearings contain minor amounts of antistatic agents, shown earlier to be potential contaminants to both bearing surfaces and lubricants. One method to eliminate the antistatic additives is to use electroactive polymers. The materials with the most promise for this application are the F ion implanted polyacetylene and polyparaphenylene. The characteristics and behavior of the polymers will be presented.
INTRODUCTION Delicate instrument components (i.e., precision gyrobearings) are extremely sensitive to atmospheric particulate contamination. To avoid such effects during storage or transport, these components are often packaged in antistatic polymeric containers, which prevent the accumulation of electrostatic charges. The currently used antistatic agents incorporated into polyethylene or nylon packaging films have shown adverse effects after extended contact with metal surfaces.(1,2) By selective ion implantation of electroactive polymers, remarkable surface resistivity lowering as well as increased oxidation stability were accomplished. Processes for improving the physical properties, such as flexibility, were also studied. After long-term contact with lubricated and unlubricated bearing steels, the modified conducting polymers and commercial antistatic materials were evaluated for adverse effects.
EXPERIMENTAL Films Polymers examined were polyacetylene, (CIH),, prepared at the Naval Research Laboratory, polyparaphenylene sulfide (PPS), and a copolymer of ethylene and methacrylic acid (COPOL); the latter two were obtained from commercial suppliers. Since unmodified (CH)x was susceptible to oxidation when exposed to air, samples were either chemically doped with 2 percent Ior PF., or ion implanted with F+ to improve their stability. To maintain flexibility during air exposure, (CH)X was deposited on polypropylene (PP) film prior to F+ implantation. PPS and COPOL, although flexible and stable, were implanted with F+ to decrease their surface resistivities. Three flexible polyethylene-based films, and a more rigid gold-coated polyester film, all commercially available antistatic or conductive materials, were also examined. Composition and selected properties of the films are summarized in Table I. All properties of the commercial films were supplied by the vendors.
Mat.
Res. Soc,
Symp.
Proc. Vol.
27
(1984)
Published by Elsevier
Science Publishing Co.,
Inc.
760
TABLE I.
Physical properties of film materials.
"TH1ICKNESS SURFACE C'oswM f I IITON
Polyacetylene (Cl ), I - doped (CH),I'FT, doped (CH),,F+ implanted (CH),F+ implanted, on polypropylene Polyparaphenylene Sulfide F* implanted Copolymer ethylene/ methacrylic acid, F+ implanted Polyethylene with slip agent Polyethylene with antistat + mylar + Al-Ti + antiabrasive Polyethylene with antistat + Al + urethane M
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